A lateral drain metal-oxide-semiconductor (LDMOS) device is a high voltage device widely used in display devices, portable devices, and many other applications. Design goals of the LDMOS device include a high breakdown voltage and a low specific on-resistance.
The specific on-resistance of the LDMOS device is limited by a doping concentration of a grade region of the device. When the doping concentration of the grade region decreases, the specific on-resistance increases.